In general, a sliding door device is applied to a large commercial vehicle such as a bus and a van so that a large number of occupants may easily get on and off.
The sliding door device includes a sliding door installed to move along a guide rail provided in a vehicle body to open and close a door opening in the vehicle body that is an entrance to the vehicle. A pneumatic cylinder, as a power source moves the sliding door, and a micro switch senses the closing of the sliding door. A controller controls the pneumatic cylinder based on a sensing signal of the micro switch to control the opening and closing of the sliding door.
In addition, the sliding door device ensures a sliding door safely closing function to prevent an object from being damaged or an occupant from being injured when the object or the occupant is jammed in a space between the sliding door and the door opening in a process of closing the sliding door where the sliding door blocks the door opening.
That is, in the sliding door safely closing function, when the object or the occupant is jammed in the space between the sliding door and the door opening in the process of closing the sliding door, the sliding door moves in a reverse direction, that is, in a direction where the door opening is opened so that it is possible to prevent the object or the occupant from being jammed.
In a method of sensing that the object or the occupant is jammed, a change in an internal pressure of a weather strip attached to the sliding door is used to release shock and to maintain air-tightness. That is, when the object or the occupant is jammed, a pressure is applied to the weather strip to generate a change in the pressure. The change in the internal pressure of the weather strip is sensed to determine whether the object or the occupant is jammed.
According to the above-described conventional sliding door device, in a predetermined range, for example 30 mm, immediately before the sliding door is completely closed, jamming of the object or the occupant is ignored, and closing of the sliding door continues, although an object such as clothes or a shoulder strap of an occupant or a part of the occupant's body is jammed in the sliding door. This ignorance purports to prevent a malfunction caused by compression of the weather strip when the sliding door is closed, but, as a result, may damage the object or injure the occupant.
On an incline, the sliding door may be closed by self-load before the micro switch senses the closing of the sliding door so that erroneous sensing in which the micro switch may not correctly sense the closing of the sliding door may be generated. In order to prevent the erroneous sensing, a point in time when the closing of the sliding door is recognized by the micro switch is set to be earlier than a point in time when the closing of the sliding door is completed at a predetermined interval, for example, 30 mm.
Therefore, even if leaving the predetermined interval before the completion of closing of the door, the jamming problem of the object or occupant still exists.
In addition, in a method of sensing that the object or the occupant is jammed, since the internal pressure of the weather strip changes in accordance with a change in peripheral temperature of the weather strip, a malfunction may be caused. For example, it is determined that the object or the occupant is jammed only when pressure of no less than predetermined pressure, for example, pressure of no less than 4.5 kgf is sensed in the weather strip.
Therefore, when an object or a part of an occupant's body of no more than, for example, 30×60 mm is jammed, it is not sensed that the object or the occupant is jammed and, thus, the closing of the sliding door continues so that the object may be damaged or the occupant may be injured and a vehicle is driven in a state where the occupant is jammed in the sliding door, which may incur a casualty accident.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.